JUMAT

Highlights

Grinding Process

Special solutions

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Technical data

Equipment and Options

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JUMAT

JUMAT - Cylindrical grinding machines

Versatile in every regard

Quality, productivity, availability – the JUMAT external and internal cylindrical grinding machine leaves nothing to be desired. Various sizes and a large number of wheelhead versions offer unrivaled versatility. Paired with the concentrated expertise of JUNKER, each machine is specially matched to the customer‘s requirements.

Highlights

High dimensional accuracy thanks to various measuring systems
Long tool life through use of CBN or diamond grinding wheels
Versatility due to a large number of wheelhead versions
Minimized undulations due to grinding wheel balancing on two levels
Fast changeover through patented 3-point mounting interface

Grinding process descriptions

The cylindrical grinding machines of the JUMAT series can perform both OD and ID grinding in a single clamping set-up. CBN and diamond grinding wheels enable high-speed grinding, provide for high cutting performance and enable grinding of difficult materials.

External cylindrical grinding: During external cylindrical grinding, the workpieces are clamped between tips or in a collet chuck. To increase productivity, grinding wheel sets are used for some applications. The JUMAT uses the straight and inclined plunge-cut grinding process.

With straight plunge-grinding, the cutting and feed movement is carried out radially to the workpiece. The diameters are ground either in one feed or with several feeds and axial twisting.

With inclined plunge-cut grinding, the grinding wheel is at an angle and the wheelhead (B-axis) is swiveled. The X and Z-axis interpolate. This makes it possible to grind the diameter and flat surfaces in a single feed.

To grind grooves or to pre-grind threads, a galvanically bonded grinding wheel is usually used.

Internal cylindrical grinding: Internal cylindrical grinding enables precise grinding of inside functional surfaces, such as drilled holes, cones or flat surfaces. High-speed grinding spindles are used to achieve the desired cutting speed, despite the smaller grinding wheel diameter.

Special solutions

Center drive

The center drive is a special drive system which clamps the workpiece in the center and drives it via a servomotor. This enables both workpiece ends to be ground at the same time.

Grinding of steering rods

In the automotive industry, electromechanical, axially parallel power steering systems are increasingly used. The JUMAT grinds the outside thread of the steering rod in as single clamping set-up from a solid blank. Pre-grinding is carried out with galvanically bonded grinding wheels, and finish grinding with vitrified bonded CBN grinding wheels.

Grinding of ball screw nuts

The double workpiece headstock, with two opposing clamping devices, minimizes the downtime when grinding threads of ball screw nuts: While grinding is being carried out on one side, loading and unloading, positioning and clamping are carried out on the other. The only downtime: Swiveling by 180 degrees in less than 3 seconds.

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1000

3000

5000

6XL

Technical data: JUMAT 1S

Wheelheader Number: 1
Grinding Length: 150 mm
Clamping Length: 150 mm
Center Height: 100 mm
Component Weight: 5 kg
Grinding Wheel Diameter: 350 mm
Swing Diameter: 80 mm
WxDxH mm (without peripherals): 1800 x 2500 x 2100
Weight: 10000 kg

Wheelhead JUMAT 1S

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Technical data: JUMAT 1000

Wheelheader Number: 1
Grinding Length: 150 mm
Clamping Length: 150 mm
Center Height: 100 mm
Component Weight: 5 kg
Grinding Wheel Diameter: 350 mm
Swing Diameter: 80 mm
WxDxH mm (without peripherals): 1500 x 2500 x 2100
Weight: 9000 kg

Wheelhead JUMAT 1000

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Technical data: JUMAT 3000

Wheelheader Number: 1
Grinding Length: 400 mm
Clamping Length: 400 mm
Center Height: 150 mm
Component Weight: 15 kg
Grinding Wheel Diameter: 350 mm
Swing Diameter: 150 mm
WxDxH mm (without peripherals): 3400 x 2800 x 2200
Weight: 12000 kg

Wheelhead JUMAT 3000

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Technical data: JUMAT 5000

Wheelheader Number: 1
Grinding Length: 700 mm
Clamping Length: 700 mm
Center Height: 170 mm
Component Weight: 130 kg
Grinding Wheel Diameter: 500 mm
Swing Diameter: 280 mm
WxDxH mm (without peripherals): 4900 x 3400 x 2350
Weight: 14000 kg

Wheelhead JUMAT 5000

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Technical data: JUMAT 6S

Wheelheader Number: 1; 2
Grinding Length: 1000 mm; 750 mm
Clamping Length: 1200 mm
Center Height: 170 mm
Component Weight: 150 kg
Grinding Wheel Diameter: 500/700 mm
Swing Diameter: 280/320 mm
WxDxH mm (without peripherals): 4100 x 3750 x 2450
Weight: 21000 kg; 25000 kg

Wheelhead JUMAT 6S

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Technical data: JUMAT 6L

Wheelheader Number: 1; 2
Grinding Length: 1800 mm; 1500 mm
Clamping Length: 2000 mm
Center Height: 170 mm
Component Weight: 200 kg
Grinding Wheel Diameter: 500/700 mm
Swing Diameter: 280/320 mm
WxDxH mm (without peripherals): 4900 x 3750 x 2450
Weight: 24000 kg; 28000 kg

Wheelhead JUMAT 6L

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Technical data: JUMAT 6XL

Wheelheader Number: 1; 2
Grinding Length: 2800 mm; 2500 mm
Clamping Length: 3000 mm
Center Height: 170 mm
Component Weight: 300 kg
Grinding Wheel Diameter: 500/700 mm
Swing Diameter: 280/320 mm
WxDxH mm (without peripherals): 6400 x 3750 x 2450
Weight: 28000 kg; 32000 kg

Wheelhead JUMAT 6XL

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Equipment and Options

LONGITUDINAL POSITIONING: A touch probe measures the longitudinal position of the workpiece on a flat surface to compensate for unmachined part fluctuations. The measured values are automatically integrated in the grinding process by the control system.
CONTROL SYSTEM: The Erwin Junker Operator Panel was specifically developed to control grinding machines. All machine components are controlled using the operator panel – irrespective of the series and the used control system. The identical structure, intuitive menu guidance and visualization of the workpiece geometry make for extreme user convenience and flexibility in operation. Programming takes place directly using the operator panel or an external programming tool.
Axis drive and guidance: The X axes, with linear roller ways with high pre-load, takes care of ultra-precise positioning of the grinding and regulating wheel head. Drive is executed by a precise, intrinsically rigid ball screw with infinitely variable servo drive and glass scale.

The B axis of the wheelheads is driven by a backlash-free gear. Every angular position is programmable; the position sensor system has a sensational resolution of 0.00001 of a degree. Extreme low noise (vibration) levels are guaranteed with the JUNKER grinding spindles with direct drive – an in-house development – complete with a structure-borne sound sensor and dynamic balancing system in one or two planes.
Clamping fixture: The patented 3-point mounting interface allows grinding and dressing wheels as well as work holdings to be mounted and centered on grinding spindles, workpiece spindles and tailstock sleeves in record time. Adjustment of the tailstock and, where applicable, the workhead take place using optionally using a chain wheel, a hydraulic cylinder or a CNC axis with rack and pinion drive. An airlift function simplifies position adjustment. Depending on the workpiece, in addition a wide range of clamping systems are also available
MACHINE BED: The machine bed made of mineral cast provides impressive damping behavior and torsional rigidity. The temperature stability allows fluctuations in the ambient temperature to be compensated with a minimum of effort, ensuring a high level of dimensional stability throughout the whole day.
IN-PROCESS MEASURING SYSTEM: A swivel-in measurement probe carries out an in-process measurement of the diameters of the main and pin bearing. The control system logs the measured values, calculates
the correction data and generates the precise shape. After grinding, the Machine is able to measure the entire geometry of the crankshaft – depending on requirements:
from the bearing width through the lift height to the taper of each element.
STEADIES: As an option, self-centering three-point steadies ensure stable support. Tracking hydraulic jaws guarantee a balanced ratio of forces at all three support points, and with it a grinding process with repeat accuracy.